Some market commentators are pointing the finger at overseas investors using KiwiSaver to try and game the New Zealand stock market.

New figures show a massive influx of foreign capital into New Zealand shares, and Castle Point Funds Management partner Stephen Bennie believes KiwiSaver could be contributing to the spike in offshore interest.

Custodial firm State Street, which looks after about US$28 trillion of assets, reports that in the past few months New Zealand has experienced one of the biggest inflows into its share market of any country measured, compared to historical averages (see chart).

In a commentary, Bennie said overseas fund managers could be trying to buy into the market ahead of future inflows from KiwiSaver funds, which would boost prices.

He described KiwiSaver as a ''massive buy order'' that would inject $400-700 million per year into the New Zealand stock exchange and rising each year, underpinning the market in a similar way to how compulsory superannuation boosted the Australian exchange in the early 2000s.

And he said the structure of the NZX 50 (seven companies account for 44 per cent of the index), combined with the passive investment strategies of most major KiwiSaver managers, made it easy to predict where this money would go.

The prime candidates include Fletcher Building, Telecom, Ryman Healthcare, Sky TV, Fisher & Paykel Healthcare and Sky City, all of which have weightings of at least 4 per cent in the NZX 50.

''In recent times all these companies have seen an increase in off shore holders.

"And all of these companies have been making new multi-year highs in 2014. To be frank, while we are being so predictable with our KiwiSavers this trend will likely continue.''

Front running is a banned practice when stockbrokers buy stocks on their own account using advance knowledge of pending orders from customers.

''If you look at simple supply and demand with KiwiSaver as the demand component, there's just not enough supply of stock,'' Coplestone said.

''When you add a layer of passive investment you can end up with a high degree of predictability as to where the money will go.''

But other experts are less convinced KiwiSaver is behind the recent surge in foreign investment on the local sharemarket.

Brian Gaynor, executive director of Milford Asset Management, said KiwiSaver could be contributing to offshore interest but there were a lot of other factors involved.''I wouldn't put KiwiSaver at the top of the ranking.

If they didn't have a positive view of the New Zealand economy and currency they wouldn't be here, even if KiwiSaver looked good.

''But Gaynor did agree that KiwiSaver strategies were too predictable, saying the big banks had a ''buy and hold'' approach that focused on the top 20 stocks on the NZX 50.

Morningstar co-head of fund research Chris Douglas said the New Zealand market was looking very attractive to overseas fund managers because of the underlying fundamentals of the economy rather than KiwiSaver.

He said overseas managers could use expected KiwiSaver flows as part of their investment strategy, but there was nothing stopping local managers and investors doing the same.

However, he said foreign managers didn't always get it right when it came to picking New Zealand stocks.

When he was in Sydney in 2006 and 2007 a lot of Australian fund managers had bought a lot of Telecom shares because they thought the share price would rise while every New Zealand fund manager had done the opposite.

The Kiwis were underweight in the stock and ''that was the right decision'', Douglas said.

Mark Lister, head of private wealth research at Craigs Investment Partners, said schemes such as KiwiSaver and compulsory saving in Australia provided some level of support to local share markets.

''It provides a regular stream of funds into that market and that money has to go somewhere. It's no different to the way immigration supports house prices: when those people come here, they need somewhere to live.''

But Lister said KiwiSaver still made up only a small portion of the overall share market (about $2 billion of the NZX 50's total market cap of $87b), and was no guarantee of stellar performance by New Zealand shares. '

'If these sorts of flows of money have such a big impact on market performance, why has the Australian share market been such an average performer over the past three years?''